8920ADC
AUDIO A-TO-D CONVERTER
Instruction Manual
071-0595-02
FIRST PRINTING: AUGUST 1999
REVISED PRINTING: SEPTEMBER 2000
2.0software release
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Grass Valley is a trademark of Grass Valley Group. All registered trademarks and trademarks are property of their respective holders. Grass Valley Group products are covered by U.S. and foreign patents,
issued and pending. Product options and specifications subject to change without notice. The information in this manual is furnished for informational use only, is subject to change without notice, and
should not be construed as a commitment by Grass Valley Group. Grass Valley Group assumes no responsibility or liability for any errors or inaccuracies that may appear in this publication.
(530) 478-3347 Grass Valley Group
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Contents
Preface
About This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
8920ADC Analog Audio to AES/EBU Converter
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Frame Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Module Placement in the 8900 Frame. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Reference Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Power Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Operation Indicator LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Local Onboard Module Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Output Level Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Configuring Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Remote Control Lockout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Remote Configuration and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Module Configuration Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Software Update Displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Signal Configuration Displays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Differential Input, Analog Gain and A/D Converters. . . . . . . . . . . . . . . . . . . . . 19
Digital Reference Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Routing and Control FPGA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Index
8920ADC Instruction Manual iii
Contents
iv 8920ADC Instruction Manual
Preface
About This Manual
This manual describes the features of a specific module of the 8900 Series
Modular Products family. As part of this module family, it is subject to
Safety and Regulatory Compliance described in the 8900 Series frame and
power supply documentation (see the
Instruction Manual
8900TX/8900TF/8900TFN Frames
).
8920ADC Instruction Manual v
Preface
vi 8920ADC Instruction Manual
8920ADC Analog Audio to AES/EBU Converter
Introduction
The 8920ADC converts analog audio to digital audio. The right and left
channel audio inputs enter via a terminal block-to-BNC adapter on the rear
panel. A 48 kHz AES/EBU reference is required to lock the module, which
is connected to the loop through input BNCs. The module outputs 4 AES/
EBU 75 Ω signals through BNCs on the rear panel.
The 8920ADC can modify the outgoing signal to provide channel swapping, channel summing, tone and phase inversion. The remote control
capability supports mode selection and input gain control. The 8920ADC
features:
■
24-bit resolution,
■
AES/EBU loop-through reference input,
48 kHz sampling rate,
■
■
Terminal block input via adapter,
■
Independent input level control from +12 dBu to +28 dBu,
8900 Series Frame compatibility,
■
■
Remote control via ethernet frame I/F, and
■
Remote control lockout via onboard jumper.
8920ADC Instruction Manual 1
1.
2.
3.
8920ADC Analog Audio to AES/EBU Converter
Installation
Installation of the 8920ADC module is a process of:
Placing the module in the desired frame slot,
Cabling and terminating signal ports, and
Configuring the module.
The 8920ADC module can be plugged in and removed from an 8900 Series
frame with power on. When power is applied to the module, LED indica-
tors reflect the initialization process (see
Frame Capacity
Power Up on page 5
).
The 8920ADC module can be installed in all 8900 Series frames but with
varying maximum quantities determined by frame cooling capacity.
Table 1 provides the power capacity, cooling capacity, and maximum
module count for each frame type.
Table 1. Power, Cooling, and Module Capacity of 8900 Frames
Capacity Calculated
Power (W) 60 60 100 100 100
Recommended Module Cooling (W) 30 60 30 90 90
8920ADC Modules 7 10 7 10 10
Note
Module capacity figures assume no other modules are in the frame.
8900T2
Frame
Module Placement in the 8900 Frame
There are ten cell locations in the frame to accommodate either analog or
digital modules. These are the left ten locations. Refer to Figure 1 on page 3.
The two cells on the right are allocated for the power supplies. For addi-
tional information concerning the Power Supply module, refer to the 8900
Frame manual.
8900T2-F
Frame
8900TX
Frame
8900TF
Frame
8900TFN
Frame
The third cell from the right is allocated for the Frame Monitor or Network
Interface controller modules. These modules provide health monitoring
and control options.
2 8920ADC Instruction Manual
Frame Monitor Module or
Network Interface Module
Any 8900 Module
Power
Supplies
(only)
0595-04r1
0595-03
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA1
J2
J4
J6
J8
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA3
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA5
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA2
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA7
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA9
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA4
J2
J4
J6
J8
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA6
J2
J4
J6
J8
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA8
J2
J4
J6
J8
J1 J2
J3 J4
J5 J6
J7 J8
J9 J10
IN
DA10
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
O
U
T
1.
2.
3.
Installation
Figure 1. 8900 Series Frame
8900 modules are interchangeable within the module cells. There are 10
BNC connectors in each cell’s I/O group. The functional assignment of
each connector in a group is determined by the module that is placed in
that cell. The maximum number of modules an 8900 frame can accept is ten.
Figure 2 illustrates the rear connector plate for an 8900 Series frame.
Figure 2. 8900 Series Frame Rear Connector
To install a module in the frame:
Insert the module, connector end first, with the component side of the
module facing to the right and the ejector tab to the top.
Verify that the module connector seats properly against the backplane.
Press the ejector tab in to seat the module in place.
8920ADC Instruction Manual 3
8920ADC Analog Audio to AES/EBU Converter
Cabling
Input
Note
At the back of this manual are overlay cards that can be placed over the rear
connector BNCs to identify the specific 8920ADC connector functions.
Connect a balanced input source to the stereo pair input terminal block (see
Figure 3).
CAUTION The input signal must be balanced. Connecting an un-balanced input signal
at high signal levels may damage the input receivers.
The 8920ADC can produce a full-scale output from an analog audio input
signal level of +12 dBu to +28 dBu.
J1
J1
J3
L+
GND
L–
8920ADC
Grass Valley
DAx
Adaptor
R+
GND
R–
O
U
T
Input/Output Connectors
J2
J4
J2
J4
J4
Analog balanced
input adapter
Figure 3.
AES reference
loop-through input
Outputs
Reference Inputs
J5
J7
J9 J10
IN
J6
J8
J6
J8
AES outputs
0595-02
The 8920ADC has four AES/EBU serial digital outputs—J5 through J8. The
destination equipment should have a 75 Ω input impedance or loop
through inputs that are terminated into 75 Ω.
Loop-through input BNCs are provided for the required 48 kHz AES/EBU
reference signals. Terminate the looping BNC into 75
Ω
if not used.
4 8920ADC Instruction Manual
Power Up
Operation Indicator LEDs
Power Up
The front LED indicators and configuration switches are illustrated in
Figure 4. Upon power-up, the green PWR LED should light and the yellow
CONF LED should illuminate for the duration of module initialization.
With factory default configuration and valid input and reference signals
connected, the green PWR LED and the green LOCK LED should be on.
Figure 4. Operation Indicator LEDs
FAULT (red)
COMM (yellow)
CONF (yellow)
PWR (green)
REM OVER (yellow)
LOCK (green)
Left In
Clip (red)
Right In
Clip (red)
Left In > -20dBFS (green)
Right In > -20dBFS (green)
A red FAULT LED indicates an error situation and, with the other LEDs,
can indicate the operational conditions presented in Table 2. The table
describes signal output and LED indications for various input/reference
combinations and user settings.
0595_06
8920ADC Instruction Manual 5
8920ADC Analog Audio to AES/EBU Converter
Table 2. Indicator LEDs and Conditions Indicated
LED Indication Condition
Off Normal operation.
FAULT
(red)
COMM
(yellow)
CONF
(yellow)
PWR
(green)
REM OVER
(yellow)
LOCK
(green)
LEFT IN
(green)
RIGHT IN
(green)
LEFT IN
CLIP
(red)
RIGHT IN
CLIP
(red)
On continuously Module has detected an internal fault.
Flashing Reference input is faulty or not present.
Off No activity on frame communication bus.
Long flash Location Command received by the module from a remote control system.
Short flash Activity present on the frame communication bus.
Off Module is in normal operating mode.
On continuously
Flashing Indicates rate of change of paddle-controlled analog setting.
Off No power to module or module’s DC/DC converter failed.
On continuously Normal operation, module is powered.
Off Module configuration matches switch and jumper settings.
On continuously
Off Module does not detect a valid AES in reference signal.
On continuously Valid AES in reference signal is present and module is locked to it.
Off Left channel level is less than -20 dBFS.
On continuously Left channel level is greater than -20 dBFS.
Flashing Left channel level is transitioning through -20 dBFS
Off Right channel level is less than -20 dBFS.
On continuously Right channel level is greater than -20 dBFS.
Flashing Right channel level is transitioning through -20 dBFS
Off Left channel digitized signal level is less than -0.5 dBFS.
On continuously Left channel digitized signal level is greater than -0.5 dBFS.
Flashing Left channel digitized signal level is transitioning through -0.5 dBFS.
Off Right channel digitized signal level is less than -0.5 dBFS.
On continuously Right channel digitized signal level is greater than -0.5 dBFS.
Flashing Right channel digitized signal level is transitioning through -0.5 dBFS.
Module is initializing, changing operating modes or updating firmware. Simultaneous CONF and FAULT LEDs on indicate FPGA load error.
Module configuration may not match switch and jumper settings. Control has been
remotely overridden.
Table 3 provides the possible input conditions and the output condition
that results.
Table 3. Possible Operating Conditions
Audio Input Condition Reference Input Condition Output Condition
Audio inputs present Valid reference input present AES/EBU serial digital output sampled at 48 kHz.
No audio input signal present Valid reference input present AES/EBU serial digital output sampled at 48 kHz. See S/N specification for level.
Audio inputs present Reference not present AES/EBU serial digital output sampled at approximately 47.992 kHz. Internal
Audio inputs present Invalid reference input Invalid AES/EBU serial digital output.
freerun clock rate.
6 8920ADC Instruction Manual
Configuration
Local Onboard Module Configuration
Configuration
The 8920ADC can be configured locally using onboard switches and
jumpers or remotely using the 8900NET network interface.
The following parameters must be set on the 8920ADC module:
■
Output level (Left and Right) – coarse and fine adjustment of analog
input levels for full scale digital outputs,
■
Output mode – channel swapping, summing, tone and phase inversion, and
Control mode – Local/remote or local control only (remote lockout).
■
The 8920ADC module can be configured locally to set parameters using the
jumpers, the rotary switch and two toggle switches shown in Figure 5 on
page 8. The CONF LED indicates status of the configuration process.
These components perform the following:
■
Jumper JP7 – sets control mode for Local only or Remote and Local.
Jumpers JP5 and JP6 – set coarse input level adjustment for left and
■
right channels.
■
SW2 and SW3 (toggle) switches – provide fine adjustment of the left
and right channel input levels.
Function (rotary) switch – selects a desired output configuration (0
■
through 9, A through F), although not all positions are used.
■
CONF (configuring) LED – when on, indicates the module is initializing or processing configuration information.
Note
Function switch positions 0 and F (Factory defaults) can be used to return the
module configuration to the original factory settings.
8920ADC Instruction Manual 7
8920ADC Analog Audio to AES/EBU Converter
Figure 5. Module Configuration Switches and LEDs
Coarse Level Setting
Pins
1-2
2-3
5-6
4-5
JP5
CONF (yellow)
SW1 – Function Rotary Switch
JP7
SW2 – Left In Level
SW3 – Right In Level
Output Level Adjustment
Pins
LOCAL –
REMOTE –
jumper across these pins
(1 – 2) locks out remote control
3
JP7
1
jumper across these pins
(2 – 3) enables remote
and local control
Remote Control Lockout
1-2
2-3
4-5
5-6
JP6
JP5
JP6
0595_05r1
To correctly adjust the 8920ADC for your digital application, determine
your maximum operating level and set the Coarse Level gain jumpers as
described below. This is the level above which digital clipping occurs.
Example Maximum Operating Level Setting
+24 dBu is a common maximum level. Using +24 dBu as the maximum
level, refer to Table 4 on page 9 to select the lowest input level range that
includes the maximum level of +24 dBu. Select the Coarse Level Setting pin
4 to 5 jumper setting (refer to Figure 5) because it is the highest level supported by that range and requires the least amount of gain to bring +24 dBu
up to 0.0 dBFS level. This will give the best signal-to-noise ratio that the
system can deliver.
8 8920ADC Instruction Manual
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Default
Position
1.
2.
3.
Configuration
Setting Maximum Operating Level
Once you have determined the proper coarse level jumper setting, perform
the following steps:
Set the Function Rotary Switch to the position marked 0 as shown at
left.
Remove the module from the frame and set jumpers on JP5 and JP6 to
the jumper setting that you determined using Table 4.
Table 4. Jumper Coarse Level Settings for 0.0 dBFS Output
Input Level JP5/JP6 Jumper Position
12 to 16 dBu Pins 1 and 2
16 to 19 dBu Pins 2 and 3
19 to 25 dBu Pins 4 and 5
25 to 28 dBu Pins 5 and 6
Return the module to the frame.
Using Level Gain Toggle Switches
Note
There are three ways to adjust the gain toggle switches to the proper level:
■
■
The toggle switches change input levels by increments of approximately
0.1 dB when held momentarily. Holding the switch up or down for about 1
second activates a continuous change mode that ramps the change rate from
about 0.1 dB per second to 0.6 dB per second. The yellow CONF LED will
flash slow (0.1 dB rate) or fast (0.6 dB rate) to indicate the change rate.
Apply the maximum level to the input (example +24 dBu) and monitor
the AES output with a meter that indicates digital level in dBFS and
adjust the toggle switch for each channel until the meter indicates
0.0 dBFS.
Because the toggle switches have a resolution of 0.1 dB, you may not be
able reach 0.0 dBFS exactly. Use the closest negative setting possible.
Apply an audio level that is -20 dB below the maximum level, (+4 dBu
for the example, +24 dBu -20 dB = +4 dBu) and adjust the AES output
as indicated on a digital audio meter to -20 dBFS.
If you have no meters calibrated in dBFS you can use the tone output
position to compare with the output level. Tone output is position E on
the Function Switch and outputs a 1 kHz tone at -20 dBFS. Note the
internal tone level indication while monitoring the AES output and
switch back to 0 or F position on the Function Switch, then adjust the
gain toggle switch to the same level as the internal tone level.
8920ADC Instruction Manual 9
8920ADC Analog Audio to AES/EBU Converter
■
Apply the maximum level to the input (example +24 dBu) and adjust
the gain toggle switch for each channel until the clip LED comes on.
This is -0.5 dBFS, and by tapping the toggle switch four more times you
will be within 0.15 dB (worst case) of the correct gain setting.
CAUTION Using a maximum level that is larger than the high end of the range setting
jumper will result in a clipped waveform and high distortion. Use the next
higher jumper setting that includes the maximum level and readjust the gain
following the instructions above.
Configuring Output Mode
The 8920ADC provides thirteen possible output configurations as shown in
Table 5. The module can be configured using the rotary switch shown in
Figure 5 on page 8. To make a configuration setting, rotate the switch to the
desired output configuration. The 16-position rotary switch selects one of
13 possible output modes. Positions B and C are not used and positions 0
and F select the same mode—the factory default.
Table 5. 8920ADC Output Mode Configuration
Switch
Position
0 Factory default – No phase inversion, channel swapping or summing
1 Channel swap – Left and Right
2 Both channels phase inverted
3 Left channel phase inverted
4 Right channel phase inverted
5 Right channel to both channel outputs
6 Left channel to both channel outputs
7 Left + Right to both channel outputs (-6 dB mono sum)
8 Left - Right to both channel outputs
9 Left + Right to Left channel output and Left- Right to Right channel output
A Left + Right to both channel outputs and both channels phase inverted
B Not used (outputs AES silence)
C Not used (outputs AES silence)
D Tone 1 to all channels (AES Silence)
E Tone 2 to all channels (1 kHz, -20 dBFS)
F Factory default – No phase inversion, channel swapping or summing
Mode Description
Remote Control Lockout
When a jumper is placed across pins 1 and 2 of jumper block JP7 (see
Figure 5 on page 8), module output mode settings are adjustable from the
Local on-board switches only. To have both Local and Remote access, set
the jumper across pins 2 and 3.
10 8920ADC Instruction Manual
Remote Configuration and Monitoring
8920ADC configuration and monitoring can be performed remotely using
the 8900NET interface in 8900TF or TFN frames (see Figure 6). This section
describes the GUI access to the module configuration functions. Refer to
the 8900NET Network Interface Module Instruction Manual for information on setting up and operating the 8900 frame network.
For remote access, make sure jumper block JP7 on the module is set for both
Local and Remote access (Figure 5).
Configuration
Note
Figure 6. 8900NET GUI
The physical appearance of the menu displays shown in this manual represent the use of a particular platform, browser and version of 8900NET
module software. They are provided for reference only. Displays will differ
depending on the type of platform and browser you are using and the version
of the 8900NET software installed in your system.
The links section lists the frame and its current modules. The selected link's Status
page is first displayed and the sub-list of links for the selection is opened. The sub-list
allows you to select a particular information page for the selected device.
Content display section displays information for the selected
frame or module (frame slot icons are also active links).
8920ADC Instruction Manual 11
8920ADC Analog Audio to AES/EBU Converter
The 8900 modules can be addressed by clicking on a specific module icon
in the frame status display or on a module name or slot number in the link
list on the left.
The 8920ADC will indicate a SMPTE Alarm fault on the Frame Status
display for the following alarms:
■
Missing or unlocked input, or
■
Board Failure.
Module Configuration Displays
The 8900 GUI provides the following links and displays for the 8920ADC
module (Figure 7):
■
Module Configuration displays showing status and slot configuration
information (location and user assigned names),
■
Signal Configuration displays, and
■
Software Update display.
The Module Configuration displays are the same for all remote controllable
8900 modules. Refer to the 8900NET manual for more information on these
displays. Some functions listed may not be supported by a particular
module. These will be indicated as not supported.
Figure 7. 8920ADC Display Links
Module Configuration
Displays
Signal Configuration
Display
Software Update
Display
Software Update Displays
The Software Update display allows you to download new software versions for the module. Refer to the 8900NET manual and the Grass Valley
Group web site at http://www.grassvalleygroup.com for complete details
and new software versions.
Signal Configuration Displays
This section discusses the Signal Configuration Displays available to set
and monitor the 8920ADC module parameters remotely.
12 8920ADC Instruction Manual
Configuration
Use
This
Link
Audio Control and Status
The Audio Control and Status display provides controls for setting the following parameters on the 8920ADC module:
■
Operational (output) mode, and
■
Fine adjustment of output levels.
Set the Operational Mode for the desired output of the module from the
thirteen selections listed below in Table 6 and shown in the menu display
in Figure 8 on page 15. After making the selection, hit the Apply button to
activate it.
Table 6. Remote Control Output Configuration Modes
Mode Name Mode Description
Default Factory default with no phase inversion, channel swapping or summing.
L/R Swap Swaps left and right channel outputs.
L/R Invert Both left and right channel outputs phase inverted.
L Invert Left channel output phase inverted.
R Invert Right channel output phase inverted.
R Mono (R to L/R) Right channel to both channel outputs.
L Mono (L to L/R) Left channel to both channel outputs.
L plus R to L/R Left plus right to both channel outputs.
L minus R to L/R Left minus right to both channel outputs
L plus R, L minus R Left plus right to left channel output and left minus right to right channel output.
(L plus R) Inv to L/R Left plus right to both channel outputs with both channel outputs phase inverted.
AES Silence AES silence on both left and right channel outputs.
1K@ -20dBFS Tone to both channel outputs.
Fine gain adjustment of the module output levels can be done with this display. Coarse gain levels must first be set up using the on-board jumpers JP5
and JP6 as described in
Output Level Adjustment on page 8
. Follow the procedures given there for adjusting the output levels using the fine gain
adjustments described below.
Adjust the fine gain in either Numeric or Sliders mode as shown in Figure 8
on page 15. The single arrows increment the value by 1x and the double
arrow will increment the value by approximately 10x. These controls will
allow you ± 6.0 dB of fine adjustment range.
Note
In Numeric mode only, values selected with the single or double arrow keys
will be enabled immediately. All other display entries, including typed in
values, require pressing Apply before the selection is enabled.
8920ADC Instruction Manual 13
8920ADC Analog Audio to AES/EBU Converter
The following status items will be reported in this display (Figure 8 on
page 15):
■
Module name – as defined on the main Status page.
Frame Location – indicates the frame name and slot number.
■
■
Left and Right Ch > -20 dBFS – indicates whether the left and right
channel digital output levels are greater than -20 dBFS (True) or less
than -20 dBFS (False).
Left and Right Ch > -0.5 dBFS Clip – indicates whether the digital
■
output clipping levels are greater than -0.5 dBFS (True) or less than
-0.5 dBFS (False).
■
Reference Signal – indicates whether the module is Locked (valid
AES in reference signal is present and module is locked to it) or
Unlocked (module does not detect a valid AES in reference signal).
14 8920ADC Instruction Manual
Indicates left and right
channel digital audio
output level status
Indicates left and right
channel digital output
clipping status
Configuration
Figure 8. 8920ADC Audio Control and Status Display
Indicates status of
input AES reference
Levels display in Numeric
Levels display in Sliders
8920ADC Instruction Manual 15
8920ADC Analog Audio to AES/EBU Converter
T
User Settings
Use
his
Link
Returns module setting
to factory default settings.
The User Settings menu allows you select the following parameters shown
in Figure 9:
■
Get Factory Default (Operation output mode to default, all audio levels
to 0 dB, and Monitor Audio Input mode to disabled).
■
Set Monitor Audio Inputs (Enabled or Disabled) to interact with the
main Status page to indicate the status of the audio inputs as shown
below.
Figure 9. 8920ADC User Settings Display
Enables or disables
audio input monitoring
on main Status page
shown below.
When disabled, Input Signal(s)
display is grayed out as shown
in this Status page example.
When enabled, Input Signal(s)
display will be green if both signals
are >-20 dBFS, yellow if either of
the input signals is <-20 dBFS.
16 8920ADC Instruction Manual
Specifications
Table 7. 8920ADC Specifications
Parameter Value
Analog Input
Number of inputs Balanced stereo pair
Connector type Terminal block
Input impedance > 20 kΩ differential
Input level range +12 to +28 dBu
Common mode rejection
Differential DC 0.25 V maximum
Common mode input voltage 20 V maximum
AES Reference Input
Signal type AES3 ID (1992) transformer coupled
Number of inputs 1 Loop-through
Input return loss >15 dB (100 kHz-10 MHz)
Sampling rate 48 kHz
Maximum jitter <200 ps RMS
Outputs
Number of outputs 4
Signal type SMPTE 276M, AES3 ID (1992)
Signal level +12 to +28 dBu input range adjustable to 0.0 dBFS
Output impedance 75 Ω
Connector type 75 Ω BNC
Coupling AC coupled
Performance (@ +28 dBU input and full scale output)
Sampling rate 48 kHz
Frequency response ± 0.05 dB relative to 1 kHz, 20 Hz to 20 kHz
Signal-to-noise ratio >102 dB unweighted, 20 Hz to 20 kHz
Interchannel crosstalk <-100 dB, 20 Hz - 20 kHz
Delay (input to output) 925 µS
Environmental
Frame temperature range 0 to 45 degrees C
Operating humidity range 0 to 90% non-condensing
Non-operating temperature -10 to 70 degrees C
Mechanical
Frame type 8900 Series
Power Requirements
Supply voltage ±12 V
Power consumption < 4.2 Watts
≥
70 dB, 50/60 Hz; ≥ 45 dB to 20 kHz
>105 dB “A” weighted, 20 Hz to 20 kHz
Specifications
8920ADC Instruction Manual 17
8920ADC Analog Audio to AES/EBU Converter
Service
The 8920ADC modules make extensive use of surface-mount technology
and programmed parts to achieve compact size and adherence to
demanding technical specifications. Circuit modules should not be serviced in the field.
If your module is not operating correctly, proceed as follows:
■ Check frame and module power and signal present LEDs.
■ Check for presence and quality of input signals.
■ Verify that source equipment is operating correctly.
■ Check cable connections.
■ Check output connections for correct I/O mapping (correct input con-
nector is used for the corresponding channel output).
Refer to Figure 4 for the location of PWR LED and Table 2 on page 6 for
proper LED indications.
If the module is still not operating correctly, replace it with a known good
spare and return the faulty module to a designated Grass Valley repair
depot. Call your Grass Valley representative for depot location.
Refer to the Contacting Grass Valley Group at the front of this document for
the Grass Valley Customer Support Information number.
18 8920ADC Instruction Manual
Functional Description
0595_01
–
+
Right In
Level,
Clip,
Error,
PLL Lock,
Mode
LEDs
Differential
Input
Receivers
& Pad
Control bus
from backplane
Clocks
Audio
AES Out 1
AES Out 2
AES Out 3
AES Out 4
4-bit Rotary
Switch
Option
Jumpers (4)
- 12 dB
- 8 dB
- 6 dB
- 12 dB
- 8 dB
- 6 dB
Pad
–
+
Left In
Pad
- 12 dB
- 15 dB- 9 dB
- 12 dB
- 15 dB- 9 dB
Stereo
24-bit
ADC
FPGA
Routing and Control
Processor
CPU
(Controller)
AES
Receiver
and PLL
AES Sync In
Test
Tone
The 8920ADC Converts an analog audio stereo pair to a 48 KHz AES/EBU
signal. Refer to the block diagram in Figure 10 while reading the following
functional description.
Figure 10. 8920ADC Block Diagram
Functional Description
Differential Input, Analog Gain and A/D Converters
The analog input is applied to a differential amplifier stage. This converts
the signal to single-ended and applies it to the coarse gain stage. Coarse
gain control pre-conditions the incoming signal before it is applied to the
A/D converters. For each channel, a six-position jumper sets the desired
coarse gain. This jumper controls the front-end pad of the unit in either a
-6 dB, -8 dB, or -12 dB mode and allows three 3 dB gain steps on the post
gain. This jumper allows input levels from +12 dBu to +28 dBu to be set to
0dBFS at the output.
The fine gain control is by two center-off toggle switches on the front of the
module. They provide a 6 dB range of fine gain adjustment in approximately 0.1 dB increments. The control takes approximately 6 to 10 seconds
to transition from minimum to maximum.
The signal is converted back to a differential signal and applied to the 24bit A/D converter, then to the Routing and Control FPGA (Field Programmable Gate Array).
8920ADC Instruction Manual 19
8920ADC Analog Audio to AES/EBU Converter
Digital Reference Input
The digital reference is applied via the loop-through input to the AES
receiver and phase-locked loop. This provides clock and data to the Control
and Routing FPGA and the A/D converters.
Routing and Control FPGA
The signals from the A/D converters are applied to the Routing and
Control FPGA. The incoming signal processing and level is determined by
the setting of one of 16 possible mode commands from a four-bit rotary
encoder switch and four signals from the level toggle switches. After processing, the signals are embedded into an AES stream and applied to the
Output Drivers.
The Routing and Control section also drives the front panel LEDs and interfaces to the Controller section.
Controller
Power Supply
The Controller interfaces with the Routing and Control FPGA, the
EEPROM and the 8900 Frame Bus. The Controller also provides the FPGA
code that is downloaded to the FPGA during boot-up.
The Controller section handles local control and monitoring, as well as
remote control and monitoring via the frame bus (when an 8900NET
module is installed in the frame). Module settings are stored in the
EEPROM for power up recall.
Power is fed from ±12 V rails of the frame’s switching power supply. Each
stage of the module receives it’s own, separate, highly regulated and filtered power source. Two-stage regulation is used in the analog section of
the ADC to reduce switching noise.
20 8920ADC Instruction Manual
Index
Numerics
20/24-bit DAC
remote indication
8920ADC
functional description
specifications 17
14
19–20
C
cabling 4
input 4
output 4
coarse level adjustment 7, 8, 13
COMM LED 5, 6
CONF (configuring) LED 6, 7
configuration 10
factory default 5
jumpers 7
LEDs 7
local on-board 7
remote 11
switches 7
connectors 3
input 4
output 4
F
Fault LED 5, 6
fault report 12
fine level adjustment
local on-board
remote 13
frame
cell locations
cooling capacity 2
module capacity 2
power capacity 2
frame status display 11
7
2
G
GUI 11, 12
I
impedance 4
input
loopthrough
specification 17
inputs
reference
installation 2
4
4
L
LEFT IN > -20 dBFS LED 6
LEFT IN CLIP LED 6
LOCK LED 6
M
maximum operating level 8
mode
output
module
block diagram
cells 3
install 3
placement 2
replacement 18
10
19
N
network 11
O
operational conditions
LED indications
output mode 10
rotary switch 10
5
8920ADC Instruction Manual Index-1
outputs
configuration
connectors 4
level adjustments 8
local on-board 9
remote 13
specification 17
termination 4
overlay 4
10
P
power requirements 17
PWR LED 5, 6
R
reference inputs 4
REM OVER (remote override) LED 6
remote control displays
Audio Control and Status
User Settings 16
remote control lockout 10
jumper 7, 10
RIGHT IN > -20 dBFS LED 6
RIGHT IN CLIP LED 6
rotary switch 7, 10
13
S
SMPTE alarm 12
T
termination 4
toggle switches 7
setting levels 9
troubleshooting 18
Index-2 8920ADC Instruction Manual
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